This invention relates to optical communication and in particular to an apparatus and method for transmitting and receiving intelligence by means of optical energy.
With the advent of the laser, many devices were soon developed for both transmitting and coding information-bearing intelligence upon the infrared, visible, and ultraviolet optical beam produced by the laser. It was quickly recognized that specific properties of its emitted optical radiation enabled its beam to carry high-density information. That is, analog or digital information which conveyed intelligence could be transmitted, received, and/or coded by means of the proper shaping and/or modulating of the laser beam.
The development of improved gas, solid state, and semiconductor lasers for feeding optical-fiber systems for transmission of information has also lead to the development of free-space or atmospheric optical systems such as is disclosed in U.S. Pat. No. 4,627,106. It is taught therein that a beam of spatially coherent, monochromatic, aperture limited, electromagnetic optical energy can be modulated with intelligence-bearing information to develop wavefronts of mutually-aligned orientation, thereafter propagated through free space and subsequently detected by a receiving means for deriving and utilizing the information provided by the demodulation.
Thus, optical free-space communication channels have been established using laser sources in both the visible and infrared spectral regions. Their high directionality is one of most appealing characteristics of laser beams and this property is often used in optical free-space communication (see U.S. Pat. Nos.: 4,764,982; 4,928,317; and, 5,457,561).
High-density communication systems are perhaps the most rapidly developing economic sector. Advances in fiber optic communication systems have brought tremendous market opportunities. One potential bottleneck in the wide spread of fiber optic systems is the xe2x80x9clast milexe2x80x9d connection to consumers as well as specific requirements of xe2x80x9clocal area networksxe2x80x9d. For obvious economic reasons, the first choice in these situations in communication systems is the broadband wireless systems. The available options are radio, microwave, and free-space optical connections. Optical free-space communication systems have definite advantages such as dense wavelength division multiplexing; no special operation licensing (unlike microwaves); ease of installation and fast deployment; and, highly secure (direct link). In principle, full benefits of fiber optic communications (speed, volume, etc) can be obtained in free-space connections.
In summary, there are requisites of novel methods of angular control and/or directional sending and receiving of radiation of one or more laser beams having the same or different wavelengths which can be used for the operation of LIDAR, LADAR, different kind of scanning systems, WDM devices for systems of fiberless optical networks.
One of the very important needs of the last noted systems is a compact, planar and easily adjustable customer unit to send and receive data through the air. This was so indicated by a Lucent Technologies Press Release entitled xe2x80x9cTerrabeam Corporation and Lucent Technologies to jointly develop and deploy Terrabeam""s breakthrough fiberless optical technologyxe2x80x9d of Apr. 12, 2000 (see http://lucent.com/press/0400/000412.coa.html) where it was stated that this unit was xe2x80x9cat the heart of TeraBeam""s solutionxe2x80x9d xe2x80x9c. . . to develop and deploy . . . fiberless optical networking system that provides high-speed data networking between local and wide area networksxe2x80x9d.
The first objective of the present invention is to improve non-confined free-space optical communications.
The second object of this invention is to provide an optical communication system consisting of transmitter and/or receiver which have spectral selectivity from one side.
The third object of this invention is to provide an optical communication system featuring a receiver and/or transmitter which is compact, planar and is easily adjustable from one side.
The fourth objective is to provide an optical communication system featuring a receiver and/or transmitter which has spectral selectivity from one side and is compact, planar and easily adjustable from the other side.
The fifth objective is to provide transmitting-receiving unit for optical communication with a design that allows a unit readjusting for any direction of transmission or reception without changing of its original plane position.
A preferred embodiment fully describing the invention representing a narrow-band transmitting-receiving telescope apparatus for optical communication is an apparatus comprising: a rotating diffraction grating; and an independently rotating stage with the mounted combination of a laser directing beam onto said grating for transmission, a photodetector, and a focusing system which concentrates the received optical beam reflected from the said grating onto said photodetector for reception whereby the selection of definite angles for signal transmission-reception is realized by a separate rotation of said grating and said rotating stage to the proper angles.
Further objects and advantages of this invention will be apparent from the following detailed description of a presently preferred embodiment, which is illustrated schematically in the accompanying drawings.